/// <inheritdoc />
protected override void OnParametersSet()
{
if (ItemSize <= 0)
{
throw new InvalidOperationException(
$"{GetType()} requires a positive value for parameter '{nameof(ItemSize)}' to perform virtualization.");
}
if (ItemsProvider != null)
{
if (Items != null)
{
throw new InvalidOperationException(
$"{GetType()} can only accept one item source from its parameters. " +
$"Do not supply both '{nameof(Items)}' and '{nameof(ItemsProvider)}'.");
}
_itemsProvider = ItemsProvider;
}
else if (Items != null)
{
_itemsProvider = DefaultItemsProvider;
}
else
{
throw new InvalidOperationException(
$"{GetType()} requires either the '{nameof(Items)}' or '{nameof(ItemsProvider)}' parameters to be specified " +
$"and non-null.");
}
_itemTemplate = ItemContent ?? ChildContent;
_placeholder = Placeholder ?? DefaultPlaceholder;
}
/// <inheritdoc />
protected override void OnParametersSet()
{
if (ItemSize <= 0)
{
throw new InvalidOperationException(
$"{GetType()} requires a positive value for parameter '{nameof(ItemSize)}'.");
}
if (_itemSize <= 0)
{
_itemSize = ItemSize;
}
if (ItemsProvider != null)
{
if (ItemsSource != null)
{
throw new InvalidOperationException(
$"{GetType()} can only accept one item source from its parameters. " +
$"Do not supply both '{nameof(ItemsSource)}' and '{nameof(ItemsProvider)}'.");
}
_itemsProvider = ItemsProvider;
}
else if (ItemsSource != null)
{
_itemsProvider = DefaultItemsProvider;
// When we have a fixed set of in-memory data, it doesn't cost anything to
// re-query it on each cycle, so do that. This means the developer can add/remove
// items in the collection and see the UI update without having to call RefreshDataAsync.
ValueTask refreshTask = RefreshDataCoreAsync(renderOnSuccess: false);
// We know it's synchronous and has its own error handling
Debug.Assert(refreshTask.IsCompletedSuccessfully);
}
else
{
throw new InvalidOperationException(
$"{GetType()} requires either the '{nameof(ItemsSource)}' or '{nameof(ItemsProvider)}' parameters to be specified " +
$"and non-null.");
}
_itemTemplate = ItemTemplate ?? ChildContent;
_placeholder = Placeholder ?? DefaultPlaceholder;
}
private RenderFragment BuildVirtualize <TItem>(
float itemSize,
ItemsProviderDelegate <TItem> itemsProvider,
ICollection <TItem> items,
Action <Virtualize <TItem> > captureRenderedVirtualize = null)
=> builder =>
{
builder.OpenComponent <Virtualize <TItem> >(0);
builder.AddAttribute(1, "ItemSize", itemSize);
builder.AddAttribute(2, "ItemsProvider", itemsProvider);
builder.AddAttribute(3, "Items", items);
if (captureRenderedVirtualize != null)
{
builder.AddComponentReferenceCapture(4, component => captureRenderedVirtualize(component as Virtualize <TItem>));
}
builder.CloseComponent();
};
